This application claims a priority based on Japanese Patent Application No. 2000-49922 filed on Feb. 25, 2000, and 2001-42973 filed on Feb. 20, 2001 the entire contents of which are incorporated herein by reference for all purposes.
The present invention relates to image display means in game machines.
In general, a casing of a portable game machine is provided with a liquid crystal display device as an image display device. Since importance is attached to portability for the portable game machine, the size of the casing has a certain limitation. Therefore, a large-sized liquid crystal display device cannot be employed, which makes it difficult to heighten the resolution of the display screen of the liquid crystal display device of the portable game machine.
A game program of the portable game machine is of ten distributed with a semiconductor device, such as a memory card or a memory cartridge, as a medium. In such a game program, image data are created in conformity with the resolution of the display screen of the liquid crystal display device included in the portable game machine.
Meanwhile, it has been considered in recently years to furnish the portable game machine with a terminal for outputting image data (external video output terminal) and to display the image of the portable game machine on the screen of a TV set or the like. Besides, it has been considered that the memory card or the like of the portable game machine is made usable also by a stationary game machine in order that the game program for the portable game machine may be enjoyed by the stationary game machine which can provide a user with superior operation feeling at his home.
On the other hand, it has been considered owing to enhancement in the processability of the portable game machine that a game program for the stationary game machine is made divertible to and usable by the portable game machine. This makes it possible, for example, to consecutively play a game for the stationary game machine by the portable game machine even when a user is out.
The resolution of the liquid crystal display device included in the portable game machine is usually lower as compared with that of the TV set to be connected to the stationary game machine. Therefore, when the image data are created in conformity with the resolution of the liquid crystal display device of the portable game machine, a display roughens on the screen of the TV set. On the other hand, when image data are created in conformity with the resolution of the TV set, alphanumeric information etc. are displayed in distorted states on the screen of the liquid crystal display device of the portable game machine.
Proposed as a technique for solving the former problem is a method wherein an original image is scaled up by processing such as interpolation, thereby to heighten an apparent resolution. Proposed as a technique for solving the latter problem is a method wherein an original image is scaled down by processing such as of a low-pass filtering.
As shown in FIG. 9A by way of example, the pictorial frame of a game contains objects having various properties, such as a character 810, a background 811 and alphanumeric information 812. In this regard, an image displayed on a display device is a result obtained in such a way that the image data of the respective objects as shown in FIG. 9B are overlapped by a graphic processing unit included in a game machine.
A technique for scaling up or down the image is such that the frame being the result of the overlap of the objects as shown in FIG. 9A is uniformly submitted to image processing. In the case of uniformly scaling up the image of the overlapped result, the display thereof is smoothened as a whole, but it cannot express, for example, the facial expression of the character not contained in the original image data. Therefore, the display by a TV set becomes unsatisfactory. On the other hand, in the case of uniformly scaling down the image, as the processing is executed irrespective of the contents of the alphanumeric information and the character, it might result in thinning out any important part of the character or containing an in-between color at the display part of the alphanumeric information. There is the possiblity that the character or the alphanumeric information will become illegible.
An object of the present invention is to provide a technique by which objects appearing in a game are displayed using image data suited to image display devices.
In order to accomplish the object, according to the present invention, the image data of objects are created for, at least, a high resolution and a low resolution, and they are recorded in a recording medium. A game machine having loaded the image data of the recording medium judges whether an image display device is one of low resolution or one of high resolution. Thus, it displays the objects by using the image data which conform to the resolution of the display device.
On this occasion, it is sometimes difficult in view of the limited storage capacity of a memory card or the like, the cost of data creation, etc. that, as to all the objects, the image data are recorded for the plurality of resolutions beforehand. Besides, even when the objects, for example, such as backgrounds have had their displays somewhat disordered by undergoing the image processing of scale-up or -down, they are less influential than the objects of alphanumeric information, characters, etc. Therefore, information which indicates whether the image data are created for the plurality of resolutions or the image of the object is scaled up or down by the image processing may well be affixed every object beforehand, so as to display the object by the method suited to the property thereof.